FINAL REPORT ZJ_EN.pdf · 2019. 4. 10. · AFIL A flight plan provided to an air traffic services...
Transcript of FINAL REPORT ZJ_EN.pdf · 2019. 4. 10. · AFIL A flight plan provided to an air traffic services...
2014-511-4
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FINAL REPORT
2014-511-4
Accident
Near Kiskunlacháza Airport
24 December 2014
Pipistrel Virus SW
14-79
The sole objective of the safety investigation is to reveal the causes and circumstances of aviation
accidents or incidents and to initiate the necessary technical measures and make recommendations in
order to prevent similar cases in the future. It is not the purpose of this activity to investigate or apportion
blame or liability.
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General information
This investigation has been carried out by Transportation Safety Bureau on
the basis of
Regulation (EU) No 996/2010 of the European Parliament and of the Council of 20 October 2010
on the investigation and prevention of accidents and incidents in civil aviation and repealing
Directive 94/56/EC,
Act XCVII of 1995 on aviation,
Annex 13 identified in the Appendix of Act XLVI. of 2007 on the declaration of the annexes to
the Convention on International Civil Aviation signed in Chicago on 7th December 1944,
Act CLXXXIV of 2005 on the technical investigation of aviation, railway and marine accidents
and incidents (hereinafter referred to as: Kbvt.),
Decree № 123/2005. (XII. 29.) of the Minister of Economy and Transport on the rules of
technical investigation of aviation accidents and incidents and other occurrences,
NFM Regulation 70/2015 (XII.1) on technical investigation of aviation accidents and incidents,
as well as on detailed investigation for operators,
In absence of other related regulation of the Kbvt., the Transportation Safety Bureau of Hungary
conducted the investigation in accordance with Act CXL of 2004.
The competence of the Transportation Safety Bureau of Hungary is based on Government Decree №
278/2006 (XII. 23.), and, as from 01 September 2016, on Government Decree № 230/2016. (VII.29.) 23)
on assignment of a transportation safety body and on the dissolution of Transportation Safety Bureau with
legal succession.
Pursuant to the aforesaid laws
The Transportation Safety Bureau of Hungary shall investigate aviation accidents and serious
aviation incidents.
The Transportation Safety Bureau of Hungary may investigate aviation accidents and incidents
which – in its judgement – could have led to more accidents with more serious consequences in
other circumstances.
The Transportation Safety Bureau of Hungary is independent of any person or entity which may
have interests conflicting with the tasks of the investigating body.
In addition to the aforementioned laws, the ICAO Doc 9756 and the ICAO DOC 6920 Manual of
Aircraft Accident Investigation are also applicable.
This Report shall not be binding, nor shall an appeal be lodged against it.
The original version of this Report was written in the Hungarian language.
Incompatibility did not stand against the members of the IC. The persons participating in the technical
investigation did not act as experts in other procedures concerning the same case and shall not do so in the
future.
The IC shall safekeep the data having come to their knowledge in the course of the technical
investigation. Furthermore, the IC shall not be obliged to make the data – regarding which the owner of
the data could have refused its disclosure pursuant to the relevant act – available for other authorities.
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This Final Report
was based on the draft report prepared by the IC and sent to all affected parties (as specified
by the relevant regulation) for comments.
Copyright Notice
This report was issued by:
Transportation Safety Bureau, Ministry for Innovation and Technology
2/A. Kőér str. Budapest H-1103, Hungary
www.kbsz.hu
This Preliminary Report or any part of thereof may be used in any form, taking into account
the exceptions specified by law, provided that consistency of the contents of such parts is
maintained and clear references are made to the source thereof.
Translation
This document is the translation of the Hungarian version of the Final Report. Although
efforts have been made to translate it as accurately as possible, discrepancies may occur. In
this case, the Hungarian is the authentic, official version.
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Table of Contents
GENERAL INFORMATION ................................................................................................................... 2
DEFINITIONS AND ABBREVIATIONS ............................................................................................... 5
INTRODUCTION ...................................................................................................................................... 7
1. FACTUAL INFORMATION .......................................................................................................... 10
1.1. HISTORY OF THE FLIGHT ............................................................................................................. 10
1.2. INJURIES TO PERSONS ................................................................................................................. 11
1.3. DAMAGE TO AIRCRAFT ............................................................................................................... 11
1.4. OTHER DAMAGE ......................................................................................................................... 11
1.5. CREW DATA ................................................................................................................................ 12
1.6. AIRCRAFT DATA ......................................................................................................................... 12
1.7. METEOROLOGICAL INFORMATION.............................................................................................. 14
1.8. AIDS TO NAVIGATION ................................................................................................................. 14
1.9. COMMUNICATIONS ..................................................................................................................... 14
1.10. AERODROME INFORMATION ....................................................................................................... 14
1.11. DATA RECORDERS ...................................................................................................................... 14
1.12. WRECKAGE AND IMPACT INFORMATION .................................................................................... 15
1.13. FORENSIC INFORMATION ............................................................................................................ 16
1.14. FIRE ............................................................................................................................................ 16
1.15. SURVIVAL ASPECTS .................................................................................................................... 16
1.16. TESTS AND RESEARCH ................................................................................................................ 16
1.17. ORGANISATIONAL AND MANAGEMENT INFORMATION .............................................................. 17
1.18. ADDITIONAL INFORMATION ....................................................................................................... 17
1.19. USEFUL OR EFFECTIVE INVESTIGATION METHODS ..................................................................... 21
2. ANALYSIS ........................................................................................................................................ 22
2.1. POSSIBILITY OF ELECTRICAL FIRE .............................................................................................. 22
2.2. PILOT ACTIVITY AND SURVIVAL ASPECTS .................................................................................. 22
2.3. THE PROCESS OF DEVELOPMENT OF THE FIRE ............................................................................ 23
2.4. LAYOUT OF THE ELECTRICAL SYSTEM OF THE AIRCRAFT .......................................................... 24
3. CONCLUSIONS ............................................................................................................................... 25
3.1. FACTUAL STATEMENTS .............................................................................................................. 25
3.2. CAUSES OF THE ACCIDENT ......................................................................................................... 25
4. SAFETY RECOMMENDATIONS ................................................................................................ 26
4.1. ACTIONS TAKEN BY THE MANUFACTURER DURING THE SAFETY INVESTIGATION ..................... 26
4.2. SAFETY RECOMMENDATION ISSUED AFTER THE INVESTIGATION .............................................. 26
ANNEXES ................................................................................................................................................. 27
ANNEX 1: DIAGRAM OF THE SCENE ........................................................................................................ 27
ANNEX 2: FLIGHT DATA RECORDED BY RADAR ..................................................................................... 28
ANNEX 3: TEST DATA OF THE CABLE OF SERIAL № M22759/16 ............................................................ 29
ANNEX 4: SERVICE BULLETIN № SB-100-004 A.02 .............................................................................. 30
ANNEX 5: SERVICE BULLETIN № SB-100-006 LSA A.00 ...................................................................... 34
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Definitions and abbreviations
AFIL A flight plan provided to an air traffic services unit by an aircraft by radio
during its flight
Ah Amper-hour
air traffic service1 A generic term meaning variously, flight information service, alerting service,
air traffic advisory service, air traffic control service (area control service,
approach control service or aerodrome control service)
ARP Airport Reference Point
ASTM American Society for Testing and Materials International, an international
standards organisation
ATS Air Traffic Service
EASA European Aviation Safety Agency
Flarm a GPS-based collision warning system
flight plan Specified information provided to air traffic service units, relative to an intended
flight or portion of flight of an aircraft
IC Investigating Committee
ICAO International Civil Aviation Organization
ITM Ministry for Innovation and Technology
Kbvt. Act CLXXXIV of 2005 on the technical investigation of aviation, railway and
marine accidents and incidents and other transportation occurrences
LiFePO4 Chemical formula of the compound lithium iron phosphate
LT Local Time
MET Ministry of Economy and Transport
MND Ministry of National Development
NTA AA National Transport Authority Aviation Authority (till 31 12 2016) (Hungary)
OKF National Directorate for Disaster Management (NDGDM)(Hungary)
transponder On-board secondary radar transponder, a receiver/transmitter that transmits a
response upon appropriate questioning; asking and answering take place at
different frequencies
TSB Transportation Safety Bureau
1 Implementing Regulation (EU) 2017/923 of 12 May 2017
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ultralight aircraft The aircraft category defined in para. e) Annex 1 to Regulation (EU)№
2018/1139 of the European Parliament and of the Council (EU)
UTC Coordinated Universal Time
VFR Visual Flight Rules
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Introduction
Occurrence category accident
Aircraft
Manufacturer Pipistrel d.o.o. Ajdovscina
Type Pipistrel Virus SW
Registration sign 14-79
Operator private person
Occurrence Date and time 24 December 2014, at about 12:48LT
Location Near Kiskunlacháza Airport (Figure 1)
Number of people severely injured in the
accident:
1
Extent of damage of the aircraft involved in
the occurrence:
Destroyed
Any clock-time indicated in this report is given in local time (LT). Time of the occurrence: LT= UTC+ 1
hours.
Figure 1: Location of the accident in Hungary
Reports and notifications
The occurrence was reported to the dispatcher of TSB by the duty service officer of OKF on 24
December 2014, at 14:00.
The duty service of TSB:
notified the investigating authority of the state of the manufacturer and designer of the aircraft on
29 December 2014.
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Investigating Committee
The Head of TSB assigned the following Investigating Committee (hereinafter: IC) for the investigation
of the occurrence:
Investigator-in-Charge Zsigmond Nagy Accident Investigator
Member Miklós Ferenci Accident Investigator
Member Gábor Erdősi Accident Investigator
Overview of the investigation
During the investigation, the IC:
visited the scene and took photos there on 24 December 2014;
took more photos and performed measurements at the scene, and removed the wreck on 25
December 2015;
notified the manufacturer and the accident investigating authority of the country of the
manufacturer of the occurrence;
analysed the wreck in a joint effort with the manufacturer;
received the video record of the battery overload test performed by the manufacturer during its
own investigation, as well as the related test report;
obtained a chemical expert’s opinion form Hungarian Institute for Forensic Science;
interviewed the pilot, requested information on the purchasing of the aircraft, on the pilot’s prior
experience with the aircraft, on the emergency situation that had emerged, and on the solution of
that situation
obtained the radar images recorded by HungaroControl Zrt. and analysed them;
overviewed the flight manual of the affected aircraft type;
consulted the relevant supervisory authority and the manufacturer on several occasions;
obtained and analysed the electrical wiring diagrams of the aircraft;
obtained the service bulletins issued by the manufacturer of the aircraft on 4 May 2017 (SB-100-
004 A.01) and 12 May 2017 (SB-100-004 A.02), as well as the service bulletin issued on 27 June
2017 (SB-100-006 LSA A.00);
obtained and overviewed the design and construction standard (ASTM) indicated by the
manufacturer, relating to the electrical system;
reviewed the data and physical properties indicated on the datasheet of the cable used for parallel
connection of the batteries, and tested certain items in practice as well;
performed a short circuit test using a battery cell which is the same type as the one involved in the
occurrence;
analysed the collected information and drew conclusions of it.
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Overview of the occurrence
On 24 December 2014, during a private cross-country flight, the pilot (and owner) of the Pipistrel Virus
SW aircraft (reg. mark: 14-79) (Figure 2) detected thick white smoke flowing forward from the space
behind the seats in the aircraft. In the given situation, the pilot decided to perform immediate emergency
landing. In an area which seemed appropriate near Kiskunlacháza airport, the pilot performed emergency
landing, during which the aircraft impacted the ground hard. The pilot suffered serious injuries, and the
aircraft was destroyed in the fire which started after the aircraft crashed to ground.
The IC found that malfunctioning of the on-board battery system of the aircraft was the cause of the
occurrence.
The IC identified a contradiction in the legislation relating to research and rescue, and proposes that a
safety recommendation be issued in order to eliminate such contradiction.
The IC identified a shortcoming in the internal procedures of the manufacturer of the aircraft, and
proposes that a safety recommendation be issued in the draft report in order to eliminate such
shortcoming.
The manufacturer of the aircraft has taken measures in the meantime which does not require that a safety
recommendation be issued.
Figure 2: The aircraft type involved in the accident (source: Internet)
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1. Factual information
1.1. History of the flight
According to his report, the pilot arrived at Tököl Airport for a cross-country flight t 10:15
on 24 December 2014. His planned route was Tököl, Csongrád, Jakabszállás Airport, and
then back to Tököl Airport. The pilot filed a flight plan of the first section (Tököl to
Jakabszállás) of his flight. After taking off at Tököl, he flew his route at 2500 ft, to
Jakabszállás Airport, with a turning point at Csongrád. After taking a few turns above
Csongrád, he landed uneventfully at Jakabszállás Airport. He asked the competent air traffic
services unit to close his flight plan.
After landing, the pilot spent about 15 minutes at the airport, and then he took off again. He
set out for the second section of his route toward Tököl Airport (Figure 3). He did not file a
flight plan but checked in by radio with the competent air information service unit at
12:30:26. He agreed with the service unit by radio that he would continue flying toward
Tököl airport without a flight plan but using the 7000 transponder code, at an altitude of
3000 ft. According to the radio communications recorded by the air traffic service, the
competent service unit did not call the aircraft by radio subsequently.
According to his statement, the pilot operated all on-board electric devices (the equipment
indicated in Section 1.18.3) simultaneously during the flight.
Figure 3: Planned flight of the 14-79 aircraft
Flying at cruise altitude between Kunpeszér and Kiskunlacháza Airport, the pilot heard a
loud bang from behind him. Intense smoke appeared in the cabin soon after, and it was
accompanied by a whistling sound. According to the pilot’s statement made during his
hearing, he looked at the on-board instruments and saw, among others, that the “Battery
Amper” and “Battery Voltage” tell-tales were outside their respective ranges. Soon after, he
stopped the engine and turned electrical power consumers off. According to his statement, he
separated the battery from the electrical system by pulling the battery main switch ring, and
opened the cabin door due to the thick fume, and looked for suitable terrain to land. As he
thought he would not reach Kiskunlacháza Airport due to intense fume and spread of the
fire, he chose an agricultural area for landing, instead of the airport (Figure 4). The pilot
remembered the white smoke but could not remember the smell of the smoke or any other
odour. Holding one hand on the control stick and keeping the left door of the aircraft open
with the other hand, he performed emergency landing. The aircraft contacted the soft,
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ITM TSB Final Report 11 / 38
swampy soil rough, i.e. the terrain did not prove appropriate for a safe landing. The aircraft
halted and stood still after a short run on the ground. Then the pilot released the seat belt and
got out of the aircraft through the left door. After leaving the aircraft, he looked back at the
front of the aircraft from a distance of 3 to 4 metres, and saw fire burning in the right hand
side of the cabin (according to direction of travel).
After the emergency landing, the pilot set off to the nearby airport walking. After walking
about a kilometre, he reached the fence of the airport and called the ambulance service with
the help of the airport staff. The National Ambulance Service was called at 12:58 on 24
December 2014. The ambulance car carried the pilot with serious burn and shoulder injury to
hospital.
Figure 4: Actual flight path of the affected aircraft and the spot where it landed (source of
map: Google Earth)
1.2. Injuries to persons
Injuries Crew
Passengers Other Pilot Flight Attendant
Fatal - - - -
Serious 1 - - -
Light - - -
Uninjured - - -
1.3. Damage to aircraft
The aircraft involved in the accident burnt out fully, and it was destroyed in the fire.
1.4. Other damage
The IC had no information on any other damage during the investigation.
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1.5. Crew data
1.5.1. Data of the pilot-in-charge
Age, citizenship, gender 35 years, Hungarian, male
License data
Type MKSZ pilot
Professional validity until 10 Sep 2020
Ratings pilot
Certificates pilot
Medical certificate valid until Class II, 08/Mar/2015
The format of the document is specified by the issuing organisation and approved by the
aviation authority, and it does not indicate which activities the pilot with the given pilot
licence can perform.
According to the pilot’s report, his flight log was destroyed in the burnt-out aircraft. The
opening entry in his new flight log was 234 hours flown, on 24/12/2014.
1.6. Aircraft data
1.6.1. General data
Class Fixed-wing ultralight aircraft
Manufacturer Pipistrel d.o.o. Ajdovscina
Type Pipistrel Virus SW
Year of manufacturing 2014
Serial number 669SWN100IS
Registration 14-79
State of registry Hungary
Date of registry 28/10/2014
Owner Private person
Operator Private person
Hours flown Number of take-offs
Since manufacturing 18.1 hours* No data
Since last periodical maintenance2 - -
* According to the pilot’s report, the on-board documents and the logbook were destroyed in
the burnt-out aircraft. The opening in new logbook was 18.1 hours, on 24/12/2014.
1.6.2. Airworthiness
Airworthiness
certificate
Date of issue 28/10/2014
Valid until 28/10/2017
Restrictions None
2 50-hour care performed on 16/06/2015
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Airworthiness
Review Certificate
Number 12/014/2013
Date of issue 28/10/2014
Valid until 28/10/2017
Date of last review 28/10/2014
1.6.3. Aircraft engine data
Class 4-stroke boxer engine
Manufacturer BRP-Rotax GmbH
Type Rotax 912 IS
Serial number 7703132
Hours flown / Cycles flown
Since manufacturing 18.1 hours
Since last periodical
maintenance
-
1.6.4. Aircraft loading data
Empty mass 289 kg
Fuel quantity at take-off 50 – 60 litres (36.5 – 43.8 kg)
Maximum take-off mass 472.5 kg
Maximum baggage mass 25 kg
Limits of centre of gravity position 267-375 mm behind the leading edge
Fuel type: (based on flight manual) 95 or Avgas 100LL
1.6.5. Faulty system and equipment information
The batteries of the aircraft and the luggage compartment were situated in the space behind
the seats. According to the manufacturer’s statement, they equipped the aircraft with two
batteries, Aerovoltz make, AVO2-16 model (LiFePO4). According to the manufacturer of the
battery, each battery is equivalent with a lead-acid battery with a capacity of 28 Ah,
producing starting currents up to 500 Amperes. The manufacturer of the aircraft connected
the batteries with each other directly, applying parallel connection. The manufacturer applied
no parallel connector or other electrical safety device for the parallel connection used.
The positive and negative branches of the insulated cables of the parallel connection run
along each other, placed in a common plastic protective cable sock (Figure 5). The protective
cable socks and the cables were fastened together by shrink sleeves at 10 cm from the cable
ends.
While examining the wreck in detail, the IC found surfaces typical of metal melting, i.e.
signs of electrical short circuit, on the positive and negative branches of the wires which
connect the two batteries. The marks of molten metal were located ca. 10 cm from the cable
poles at the assumed place of the shrink sleeve (or in its close proximity) which fastens the
protective cable sock and the positive and negative cables. The position of the IC is that the
short circuit developed as a consequence of the accident.
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Figure 5: The pair of cables damaged in the accident vs. a new one
1.7. Meteorological information
The weather was clear and dry on the day of the occurrence, with patches of fog in the
Transdanubian area in the morning, which then cleared during the day. South-west wind
became strong from time to time in the area of the Great Plain and Budapest. The peak
temperatures were between 6°C and 15°C.
On 24 December 2014, at 12:30pm LT, the wind direction was 210, with a wind speed of 9
knots, according to the weather report published at Budapest Liszt Ferenc International
Airport. Visibility was over 10 kilometres, the temperature of the air was 9°C, and its dew
point was 4°C.
1.8. Aids to navigation
The navigation equipment had no effect on the course of events so it needs no further
discussion.
1.9. Communications
During flight, the pilot maintained two-way radio contact with the competent aviation
information service. The communication equipment had no effect to the occurrence therefore
detailing them is not relevant.
1.10. Aerodrome information
The planned destination airport of the second section (Figure 3) of the route was Tököl
Airport. The take-off directly preceding the occurrence took place at about 12:45 on 24
December 2014. According to the pilot’s statement, he spent 10 to 15 minutes at
Jakabszállás airport after landing then he took off again.
Actual landing took place near Kiskunlacháza airport, at about 12:48 on 24 December 2014.
Aerodrome parameters had no effect on the occurrence, so detailing them is not relevant.
1.11. Data recorders
There was no data recorder on-board the aircraft; it is not required for the given aircraft type.
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The aircraft was equipped with transponder equipment which was in operation during the
occurrence until the pilot turned electricity off. The IC obtained and used the radar image
recorded by the air traffic management service.
1.12. Wreckage and impact information
The wreck of the aircraft was found at the location with coordinates N47.16886° and
E019.09895°. The area of the emergency landing is a boggy terrain with swampy surface,
partly covered with water. The wreck was found in the 302° direction as seen from the point
of landing, at a distance of ca. 49 metres. The marks in the terrain show that the aircraft hit
the ground with high energy, which is supported by the fact that the nose gear broke out. In
its still position, the direction of the aircraft deviated 90° to the left from the direction of
landing (Figure 6 and Annex 1).
The burnt-out composite material of the airframe of the aircraft made it extremely difficult to
perform further investigation to comprehensively assess the mechanical damage suffered by
the aircraft as a consequence of the landing.
On the basis of the investigation of the scene and the detailed analysis of the wreck
performed in January 2015, the IC found that the source of the fire was not in the engine
compartment. In addition, it was also found that the area most exposed to fire was the space
behind the pilot’s seat.
Figure 6: The wreck and the area where it landed
1.12.1. Damage to fuel system
The electrical fuel pump is situated behind the right seat of the aircraft; it is fastened to the
bottom of the airframe. During the investigation of the scene, the IC found the fuel pump
which was exposed to higher thermal load at the side where the fuel lines connect to it than
the opposite side.
The opinion of the IC is that, due to hard landing, leakage developed in that section of the
fuel system which is behind the seat. Ignition of the small amount of fuel which leaked into
the airframe caused further damage to the fuel system. The larger amount of fuel that spilt
subsequently ignited all combustible parts of the aircraft.
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1.13. Forensic information
On the basis of the chemical expert opinion received from Hungarian Institute for Forensic
Science, the pilot’s blood and urine sample showed 0.00 g/l ethanol concentration.
According to the discharge note issued on completion of the pilot’s hospitalisation, the back
of the pilot’s right hand suffered serious burn, his right ear and the adjacent area got singed,
and his left shoulder got dislocated in the accident. No burn in the respiratory tract was
suspected when he was hospitalised, and he had no airway complaints during his stay in
hospital.
1.14. Fire
During the flight, the pilot heard a loud bang and then a whistling sound, which was
followed by intense white fume in the cabin; the smoke came from the space behind his seat,
so he opened the cabin door.
The aircraft burnt out fully after landing (Figure 6).
1.15. Survival aspects
Due to the thick fume and the rise in temperature, the pilot decided to perform emergency
landing. In the given situation, he did not know how much time he had before he would get
incapacitated or before the suspected on-board fire would cause structural damage that
excludes further flight.
According to the pilot’s report, he was wearing overall made for air pilots at the time of the
accident. Injured in the accident, he walked to Kiskunlacháza Airport, which was about 1
kilometre away, and made an emergency call using a cell phone borrowed from the airport
staff.
1.16. Tests and research
During the safety investigation of TSB, the manufacturer of the aircraft performed an
overload test of a battery of the type which is used in aircraft similar to that destroyed in the
accident, took a video record of it, and made the video available to the IC of TSB. Prior to
the test, the manufacturer measured the terminal voltage of the battery used for the test,
which was 14.36 V. According to the manufacturer’s information the battery used for the test
prior to and during the test was fully charged and its temperature was 18-25°C. During the
test, the battery was shorted using a cable (silicone-insulated)) which was thicker than the
battery linkage cables installed in the aircraft. The battery emitted a considerable amount of
smoke at high speed during the test (Figure 7). According to the video record, smoke
generation was accompanied by a whistling sound. The shorted battery did not catch fire, nor
did its plastic housing crack.
The IC performed detailed inspection of the wreck at the factory in Slovenia, during which a
set of socket wrenches, a first aid kit and 7 small Lithium ion batteries (type 18650) were
found. According to the pilot’s report, the latter were accessories to a handheld electrical
screw driver. According to the pilot’s report he really stored these items in the luggage
compartment. He said he had kept the socket wrench set and the wireless electrical
screwdriver so that he could remove and put back the cover plates of the wheels when
servicing the landing gear. Each of the batteries found had a nominal capacity of 24.Ah. In
its report issued on 26 January 2016, the manufacturer assumes that these batteries might
have played a role in the starting of the fire.
The small Lithium ion batteries of the handheld screwdriver were tested for short circuit on 5
March 2018. The test procedure was as follows: the IC created a short circuit involving one
battery, and then continuously measured the terminal voltage and the temperature of the
battery. The highest temperature thus measured was 96.9°C. The battery did not catch fire
during the short circuit, and neither smoke nor acoustic effect was detected. The energy
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stored in the battery was consumed in 1.5 to 2 minutes. During the period of load, its
terminal voltage dropped so much that it could not be measured. The terminal voltage of the
battery measured after the test was 0.17V, i.e. dropped largely as compared to the initial
value of 3.6V.
Figure 7: Smoke was emitted by the battery after an electrical short circuit
On 25 August 2018, the IC performed a heat shock test a piece of cable of the same type as
the one used to connect the batteries. The test procedure was as follows: a piece of cable was
placed, for 2 hours, into an oven pre-heated to 210°C. After the sample was cooled to room
temperature, no change was seen, neither by naked eye, nor under a magnifying glass. Its
mechanical properties showed no change either, as compared to the initial state. When the
cable was pushed into gas flame from the side, its insulation disappeared at the surface
which contacted the flame, but no self-sustaining fire was started in the insulation material.
The results of the test performed by the IC did not differ significantly from the test values
published by the manufacturer. See published data in Annex 3 below.
1.17. Organisational and management information
When visiting the manufacturer, the IC was informed that the manufacturer had no
elaborated and approved procedure in place relating to the framework and limits of fulfilling
customer needs. According to oral information, the quantity of installation of optional
instruments and on-board equipment is limited only by the physical dimensions of the
aircraft. Also, they have no procedure relating to the number or array of batteries to be used
for given quantities of instruments. In the case of aircraft layouts which differ from default
instrumentation the electrical network is designed with individual solutions of which no
wiring diagram is drawn up that would be valid for the aircraft of the given serial number.
That process was followed also in the case of the aircraft destroyed in the fire.
During the safety investigation, the IC asked the manufacturer for information and data
relating to the electrical system of the aircraft, but some of the questions had not been
answered by the closing of the investigation.
1.18. Additional information
1.18.1. The cable used between batteries
The cable used to connect the batteries provided for the IC by the manufacturer was type
M22759/16-6. The diameter of this cable is ca. 6mm (insulation included), and consists of
multi-stranded tinned copper wires and ETFE (ethylene-tetrafluoroethylene) insulation. Its
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usual temperature range of operation is between -55°C and 150°C. Its insulation resists
mechanical and chemical impacts very well and also has good fire resistance capability.
1.18.2. Parallel connection of batteries
The aircraft destroyed in the accident was manufactured in the Slovenian factor where it was
equipped with two type Aerovoltz AVO2-16 batteries, each with a capacity equalling that of
a 28 Ah lead-acid battery, producing up to 500 Ampere starting current, and the batteries
were connected in parallel, without a control/protection unit.
The batteries need to be connected in parallel if the amperage of the output current must be
increased. The combined amperage of the output current of the batteries connected in this
manner equals the total of the added up ampere values of the output current of each battery.
When applying connection in parallel, care must be taken to connect batteries with the same
characteristics (identical physical and electrical properties), and to install a control/protection
unit between them. Otherwise connection will cause damage.
According to the manufacturer’s declaration and the wiring diagram sent, the manufacturer
installed no protection against overload or any other protection between the batteries
connected in parallel.
During the safety investigation, the manufacturer did not tell the IC which of the aircraft
manufactured by them had an electrical system containing batteries connected in parallel.
1.18.3. Aircraft equipment
When buying the aircraft, the owner requested the manufacturer to install extra on-board
equipment in addition to the standard items. Table 1 shows the list of the optional electric
power consumers installed accordingly. The manufacturer added an additional battery to the
electrical system, placing it at the right hand side of the space behind the pilot.
Table 1
Electrical equipment Type
2 x Dynon Skyview SV-D1000 T
Auto Pilot Servo1 Dynon Sv32
Auto Pilot Servo2 Dynon Sv42
GPS Skyview SV-GPS-250
AdaHRS Skyview Sv-Adahrs-200
Flarm – ADBS Garrecht TRX-2000
Dynon Modul SV-EMS-221
Transponder Dynon SV-xpndr-281
Radio Funke ATR 833
1.18.4. Electrical feedback of on-board instruments
According to the User Guide of the SkyView Touch (SV-D1000 T) on-board instrument,3
the instrument indicates the voltage and amperage of the electrical system on a continuous
basis. Should any parameter value go outside the limits, the equipment will give an acoustic
signal and display a caution with the appropriate label: “Electrical Current HIGH” or
“Electrical Current LOW” or “Voltage HIGH” or “Voltage LOW”.
3 SkyView Touch Pilot’s User Guide, Document 101321-025, Revision Z
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1.18.5. Prior flights
The owner had his aircraft transported in disassembled state. Prior to the accident, he did not
perform any flight lasting longer than about half an hour. His first longer flight was the one
which ended up in an accident, and all the items of the electrical equipment on-board the
aircraft were in operation simultaneously.
1.18.6. Construction standard applied with the aircraft
According to the manufacturer, they applied the Standard № ASTM2639 for the electrical
systems during manufacture. According to that standard,
Power Feeder
They shall be given special protection to prevent potential chafing against other wiring
aircraft structure, or components.
9.7.1.1 Philosophy of Aircraft Circuit Protection—For reliable circuit protection, the design
shall provide automatic protection that will limit a fault to single circuit and more
importantly minimize the danger of smoke and fire not only to the component but also the
conductors (or cables) leading to and from the component. The primary consideration shall
be the protection of the conductors or cables. Furthermore, the protection shall be capable
isolating the fault from the power source so that nonfaulted circuits can be kept functioning
in a normal manner. This is an essential safety of flight requirement. These objectives may
not always be achieved by a single protective device, but by a combination of devices, wire
size, and routing. Circuit designers shall use every means available to accomplish optimum
protection. For example, correct sizing of wire and safe routing shall contribute to the
overall circuit protection philosophy. Considerations for maintenance, inspection, and
continued airworthiness shall be an integral part of the design philosophy.
Circuit protection devices shall be sized to supply open circuit capability. Proper selection
should normally result in a protective device with the lowest standard rating that will not
open inadvertently. It shall interrupt the fault or overload current by disconnecting the
faulted line from the power distribution system before wire fusing, insulation damage, or
other system damage occurs. Conventional circuit breakers shall be of the push-pull type to
facilitate periodic cycling the breakers to remove contaminants from the contacts.
III. Electrical systems and equipment
LTF-UL 1365 Electric cables and equipment
1. Each electric connecting cable must be of adequate capacity and correctly routed,
attached and connected so as to minimize the probability of short circuits and fire hazards.
1.18.7. Aircraft flight manual
According to the emergency chapter of the Flight manual and Maintenance manual 4 in effect
at the time of the occurrence:
Smoke in cockpit
Smoke in cockpit is usually a consequence of electrical wiring malfunction. As it is most
definitely caused by a short circuit it is required from the pilot to react as follows:
1. Master switch to I (key in central position) - or Avionics OFF. This enables unobstructed
engine operation while at the same time disconnects all other electrical devices from the
circuit. Verify that the 12 V and Pitot heat are OFF as well.
2. Disconnect the battery from the circuit (pull battery disconnection ring on the instrument
panel’s switch column)
3. Land as soon as possible.
4 Flight manual and Maintenance manual, REV. 3 (28 September, 2010)
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In case you have trouble breathing or the visibility out of the cockpit has degraded severely
due to the smoke, open the cabin door and leave it hanging freely. Flying with the door open,
do not, under any circumstances exceed 90 km/h (50 kts).
Flight manual and Maintenance manual5 of the aircraft requires the following procedure for
emergency landing:
Emergency landing / Landing out
1. Shut both fuel valves
2. Master switch OFF.
3. Approach and land with extreme caution, maintaining proper airspeed.
4. After having landed abandon the aircraft immediately.
The landing out manoeuvre MUST be performed with regard to all normal flight parameters.
According to the service and maintenance chapter of the Flight manual and Maintenance
manual5, the owner is entitled to service and replace the batteries. The Flight manual and
Maintenance manual specifies 12V and 11Ah values for the batteries.
1.18.8. De-energising the aircraft
The electrical system of the type Pipistrel Virus SW aircraft was designed in such manner
that the powers supply to all electrical power consumers can be shut off by pulling a ring
located on the instrument panel.
1.18.9. Research and rescue
According to the Decree № 16/2000 (XI. 22.) KöViM in effect at the time of the occurrence:
4.1.2. Alerting service shall be provided for:
a) all aircraft provided with air traffic control service;
b) all aircraft having filed a flight plan, after receiving information on their
operation, until their closing of their respective flight plans;
c) all known aircraft participating in the traffic of airports with an AFIS unit; and
for
d) any aircraft known or believed to be the subject of unlawful interference.
Note: Detailed rules of providing alert services by ATS units are specified in Chapter 9 of
Annex 2 to this Decree.
Pursuant to SERA.10001 Section 10 Annex to Commission Implementing Regulation EU
No 923/2012 (hereinafter: “SERA”) in effect at the time of the closing of the investigation:
(a) Alerting service shall be provided by the air traffic services units:
(1) for all aircraft provided with air traffic control service;
(2) in so far as practicable, to all other aircraft having filed a flight plan or otherwise known
to the air traffic services; and
(3) to any aircraft known or believed to be the subject of unlawful interference.
5 Flight manual and Maintenance manual, REV. 3 (28 September, 2010)
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According to Article 2 of SERA:
‘air traffic service (ATS)’ means a generic term meaning variously, flight information
service, alerting service, air traffic advisory service, air traffic control service (area control
service, approach control service or aerodrome control service);
Subsection (2), Section 18 of Decree № 56/2016 (XII. 22.) NFM on the Rules of the Air
within the Aerodromes of Hungary in effect at the time of the closing of the investigation
says:
”Air traffic service, including taking the actions necessary when an aircraft is in
emergency or lost as well as starting search and rescue as soon as possible, shall be
provided for the aircraft if it filed a flight plan to the ATS unit previously.
1.18.10. Burning of the fuel and of structures made of composite
According to a document addressing the burning of aircraft structures made of composite
material,6 Epoxy plastics resist an ignition temperature of 400°C. It may be stated in general
that most of the epoxy plastics used in the aviation industry have good thermal insulation
properties, and that they emit thick, black and highly toxic fumes when burning.
When kerosene is ignited in the open air, first its vapour burns. This burn is fast, produces a
lot of heat, and produces hardly any fume. Soot will float in the air after the fire is out. Next,
the emitted vapour will burn on the surface of the kerosene puddle. The amount of the fume
depends on the amount of available oxygen; its fume is dark and occasionally contains a
considerable amount of soot.
1.18.11. Service bulletins issued by the manufacturer
In its Service Bulletin № SB-100-004 A.02 issued on 12 May 2017, the manufacturer of the
aircraft provides for mandatory disconnection or removal of the second battery (See Annex
4) for all Virus SW aircraft if such aircraft is equipped with two LiFePO4 batteries connected
in parallel.
On 27 June 2017, the manufacturer of the aircraft issued a non-mandatory service bulletin
(№SB-100-006 LSA A.00, see Annex 5) for the aircraft specified in the aforesaid Service
Bulletin № SB-100-004 A.02. In the case that two batteries need to be installed in the
aircraft, the manufacturer requires installation of a specific battery type (selected by the
manufacturer) which contains appropriate protective elements.
1.19. Useful or effective investigation methods
TSB started a safety investigation under № 2011-160-4P to reveal the cause of the aviation
accident which took place on 3 August 2011. The investigation revealed that divergence can
be seen between the texts of Chapter 4 Alerting Service in Annex 1 to Decree № 16/2000
(XI. 22.) KöViM on the Rules of the Air within the Aerodromes of Hungary and Chapter 5
Alerting Service in Annex 11 Air Traffic Services identified in the Appendix of Act XLVI.
of 2007 on the declaration of the annexes to the Convention on International Civil Aviation
signed in Chicago on 7th December 1944. In order to exclude diverging provisions, TSB
issued a safety recommendation under № BA2011-160-4P-1 on 10 September 2013.
6 COMPOSITE MATERIAL FIRE FIGHTING, Federal Aviation Administration – US, 2009
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2. Analysis
2.1. Possibility of electrical fire
In a set of two batteries connected in parallel if the charge level or capacity of the one is
different from the other, then the battery which is in better state will work in charge
equalisation mode. Added to the power uptake of all electrical consumers connected and
turned on, this process may generate a significant extra load which may exceed the ratings of
the system.
On the basis of the contents of Chapters 1.16 and 1.18.1, the IC excluded the possibility that
the cables running parallel (and providing parallel connection of the batteries) could have
been damaged by friction caused by rubbing of the cables with each other or with the
airframe, and accordingly, the possibility of short circuit due to damage by friction as well.
According to information presented in Chapter 1.6.5, the electrical short circuit (melt)
occurred either at the assumed location of the shrink sleeve on the cables connecting the two
on-board batteries or in its close proximity. During the experiments performed by the IC
with the electrical cable which connects the two batteries, the insulation of the cable was
only damaged as an effect of naked flame (see Chapter 1.16 above).
The position of the IC is that, during the flight leading to the accident, one of the two
batteries connected in parallel behaved like the battery which was exposed to short circuit
during the short circuit test (see Chapter 1.16 above) performed by the manufacturer of the
aircraft.
According to the pilot’s report, he only detected white fume during the flight, which allowed
the IC to conclude that the composite structure of the aircraft was not on fire in that period.
On the basis of the pilot’s report, the conclusion drawn by the IC, and those presented above,
the battery system which malfunctioned in the occurrence could not deliver sufficient
amount of thermal energy to ignite the composite structural elements of the aircraft.
The arc discharge found on the cables used for parallel connection (Chapter 1.6.5) might
have occurred as an effect of considerable external heat, during which the insulation of the
cable was damaged. According to the opinion of the IC, such considerable external (i.e. not
coming from an electricity malfunction) heat was provided by the burning fuel. The safety
investigation brought no clear evidence relating to how the fuel system of the aircraft had got
leaked as a consequence of the high-energy impact with the ground and how the powered
section of the electrical system had ignited spilt fuel.
During the investigation, the IC excluded the possibility that (in the case of a possible short
circuit) the batteries of the handheld screwdriver on-board at the time of the occurrence (see
Chapter 1.16) could have provided sufficient heat to damage the structure of the aircraft.
2.2. Pilot activity and survival aspects
According to radar information obtained, the pilot was flying from Jakabszállás toward
Tököl at an altitude of 2900 ft. Radar data shows that, when approaching Kiskunlacháza
Airport, the pilot began to descend at 12:45:21, and simultaneously, he turned left of the
direction of flight and flew in the direction of Kiskunlacháza Airport (Figure 8).
The position of the IC is that the intense spread of the fume distracted the pilot from
controlling the aircraft to such extent that he could not pay sufficient attention to the landing
manoeuvre. This and the unsuitable terrain chosen for landing caused the primary damages
to the structural elements of the aircraft.
The pilot’s shoulder injuries suffered in the accident support that he was holding the open
door at the moment of touch down. Relying on forensic data, the IC supposes that the pilot
suffered his burn injuries after touch down, during his leaving the aircraft. The burn injuries
behind the pilot’s right ear support the supposition of the IC that the pilot was not wearing
his headset already when the blaze started. Due to the injury of his left shoulder, the pilot
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was able to use his right hand only to leave the aircraft; accordingly, his right hand was
probably more exposed to the fire. According to the position of the IC, the pilot would have
left the aircraft with injury to his respiratory tract if the aircraft had been blazing fiercely
already in the air or right after touch down.
The legal contradiction between the regulations mentioned in Chapter 1.18.9 and in the
safety recommendation (BA2011-160-4P-1) in Chapter 1.19 relating to the initiation of
search and rescue action existed before and at the time of the occurrence, and had not been
resolved by the time of the closing of the investigation.
With reference to the SERA paragraph presented in Chapter 1.18.9, the position of the IC is
that, due to the fact that the pilot contacted the competent air traffic services unit, such unit
took notice of the aircraft, and thus, they should have provided alerting service for such
aircraft. The time which elapsed between notification to the rescue units and the start of the
radio contact was not sufficient to evoke the commencing of alert on the part of the air traffic
services.
On the basis of the facts that the pilot turned his aircraft in the direction of the nearby airport
and did not start emergency landing after detecting smoke, and that he de-energised the
aircraft one minute after detecting smoke, the IC concludes that the situation was worsening
gradually as compared to the initial moment of the occurrence.
The pilot’s chances for survival were reduced by low temperatures of the atmosphere and the
water covering the swamp and by his having to walk on his own a relatively long distance to
get help.
The pilot’s chances for survival were increased by the fact that his injuries did not prevent
him from leaving the aircraft and getting help on his own.
Figure 8: The last section of the flight path of the aircraft with reg. mark 14-79 on the basis
of the radar image (source of map: Google Earth)
2.3. The process of development of the fire
According to the hypothesis of the IC, which is based on the information gathered during the
investigation, the process of destruction of the aircraft with reg. mark 14-79 took place as
follows:
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Malfunction of a battery cell was detected as noise and smoke, and interpreted as a
starting on-board fire, by the pilot;
The pilot modified his flight by turning in the direction of Kiskunlacháza Airport,
and decided to perform emergency landing when the smoke began to get thicker, and
landed as soon as possible in an area which seemed appropriate;
The IC does not know the extent of damage caused by the landing to the aircraft but
it was significant on the basis of the traces;
Structural damage to the aircraft was accompanied by a minor leakage of the fuel
system;
As a result of leakage, a small amount of fuel spilt in the behind the pilot’s seat
where the pair of batteries, connected in parallel, were also situated. The system,
which was isolated from all on-board electrical systems but contained a
malfunctioned battery in configuration of parallel connection, ignited the vapour of
the fuel spilt in its proximity. This is also supported by the pilot’s burn injuries
suffered in the accident. According to the IC’s opinion, the pilot was injured either
right before or during his leaving the aircraft.
The fire of the ignited fuel further damaged the structural elements of the aircraft as
well as the insulation of the cable pair connecting the batteries in parallel;
The cables connecting the batteries were heated and part of their insulation melted;
In the case of the cables of opposite polarity running immediately along each other,
the insulation, which melted at a point, lost its isolating function and allowed an
electric arc to occur. That caused the damage, typically the mark of short circuit, in
the pair of cables of the parallel connection (see Chapter 1.6.5).
The heat of the fuel which leaked from the fuel system and began to burn ignited the
composite airframe.
2.4. Layout of the electrical system of the aircraft
According to the pilot’s statement, when he detected the thick fume and saw the warnings on
the on-board instruments, he de-energised the aircraft. Shut-off of the electrical system does
not isolate the two batteries from each other, i.e. the risk of a short circuit is still there.
In the opinion of the IC, if a circuit protection device had been installed between the two
batteries, which were connected to each other directly, then the risk of malfunction of the
batteries and formation of a short circuit would have decreased considerably.
In the opinion of the IC, batteries connected in parallel without circuit protection are not
safe, which is also supported by the standard (referred to in Chapter 1.18.6) followed by the
manufacturer.
In order to assist assembly, the factory provides assemblers with a set of wiring diagrams for
the standard equipment of its aircraft, which does not include a process of selecting a
standard wiring diagram adjusted to specific equipment demand.
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3. Conclusions
3.1. Factual statements
The occurrence was evoked by malfunction of one of the batteries installed behind the pilot’s
seat.
Ignition of the airframe did not occur in flight.
Damage to the airframe was caused by high-energy impact with the terrain.
The airframe was ignited by the burn of spilt fuel.
The most intense fire occurred in the space behind the seats.
The pilot suffered burn injuries after the aircraft hit the ground.
The pilot had appropriate licence and ratings and sufficient experience for the given flight
task at the time of the occurrence.
During the pre-flight inspection on the ground, the aircraft was found airworthy. The aircraft
had a valid airworthiness certificate.
The take-off weight of the aircraft was within limits. The aircraft was fuelled sufficiently for
the flight.
The flight took place at daytime, in good visibility conditions.
During the investigation, the IC found electric cables which connected the two batteries, and
the cable surfaces showed a molten area which was a consequence of the fire which had
started before.
According to the manufacturer’s statement, the second batter installed in the aircraft was
connected in a parallel configuration. The manufacturer applied no parallel connector or
other safety device when connecting the two batteries. The whole electrical system of the
aircraft did not comply with the standard the manufacturer referred to.
The batteries of the handheld electrical screwdriver did not contribute to the occurrence.
The manufacturer did not have a procedure in place which would clearly specify the layout
of the electrical system.
3.2. Causes of the accident
As an outcome of the investigation, the IC concludes that the cause of the occurrence was
that smoke was formed in the aircraft due malfunction of the battery system, which the pilot
interpreted as fire on board.
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4. Safety recommendations
4.1. Actions taken by the manufacturer during the safety investigation
Relating to on-board batteries, the manufacturer of the aircraft issued the service bulletins
mentioned in Chapter 1.18.11.
The manufacturer of the aircraft, upon receiving the draft report, informed the IC that
Standard Practice for Design, Alteration and Certification of Aircraft Electrical Wiring
System manual was developed which was issued on 18 March 2019.
By its letter of 20 March 2019, the manufacturer of the aircraft informed the IC that an
electrical load analysis should be performed for each aircraft leaving production in order to
verify power consumption and generation balance.
After evaluation of the manufacturer’s action, the IC withdraws its Safety Recommendation
№ BA2014-511-4-2 included in the Draft Report sent by the IC.
4.2. Safety recommendation issued after the investigation
As a conclusion of the technical investigation, the IC finds it necessary to issue the following
safety recommendations:
BA2014-511-4-1: During its safety investigation, the Investigating Committee of
Transportation Safety Bureau found that there is contradiction between the respective
paragraphs relating to search and rescue of aircraft in Commission Implementing
Regulation EU No 923/2012 and Decree № 56/2016 (XII. 22.) NFM. For this reason:
Transportation Safety Bureau recommends the Minister for Innovation and
Technology, as the minister responsible for transport, to consider
amendment of the national regulations to ensure harmonisation of
legislation.
The opinion of the IC is that, in the case of accepting and implementing this
recommendation, the text in the relevant regulations would become unambiguous and offer
one interpretation only.
Budapest, 10 April 2019
……………………… ………………………
Zsigmond Nagy Miklós Ferenci
Investigator-in-charge IC Member
………………………
Gábor Erdősi
IC Member
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ANNEXES
Annex 1: Diagram of the scene
(RP – aircraft heading, 1 – traces of landing, 2 – spot where nose gear was found, 3 – left wing tip, 4 –
right wing tip, 5 – tail piece)
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Annex 2: Flight data recorded by radar
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Annex 3: Test data of the cable of Serial № M22759/16
Source: www.glenair.com
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Annex 4: Service Bulletin № SB-100-004 A.02
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Annex 5: Service Bulletin № SB-100-006 LSA A.00
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